Screening for disease is a paradigm of modern medical practice. In particular, newborn or neonatal screening is the practice of testing newborns for certain harmful or potentially fatal disorders that are not otherwise apparent at birth. Generally, blood drops are obtained from the heel, finger or the ear and then absorbed onto filter paper to produce a dried blood spot collection card, often referred to as a Guthrie card. The dried blood spots are tested for a variety of individual diseases and conditions, including those of metabolic, genetic, and/or hormonal origin. Because most of the United States mandate newborn screening, there is significant motivation, from both the economic and medical practice perspectives, for the development of rapid screening methods having a low overall cost. This testing saves millions of dollars per year in health care costs for treating people who would suffer the long-term effects of these disorders and diseases if not treated upon birth.
Many of the tests performed in routine newborn screening are tests that measure the enzymes or metabolites in blood by immunoreaction or tandem mass spectrometry, which correlate the markers to metabolic disorders. However, with the growing number of identified DNA biomarkers for genetic disorders, it is increasingly desirable to isolate DNA from blood samples in order to identify the DNA biomarkers therein, preferably in a high throughput multi-well format. The isolation of DNA from blood samples, especially dried blood samples, is generally a laborious process involving multiple buffers as well as multiple pipeting and aspiration steps which is not readily amenable to a high throughput format and automation. In addition, blood contains many contaminants such as lipids and proteins that can interfere with subsequent analysis steps, such as DNA amplification. The quality of the DNA extracted from blood is particularly important, for example, in the analysis of single copy number genes for which the signal to noise ratio is critically important.
What is needed are improved methods and kits for the extraction of DNA from blood samples.